It has been common practice to search data, for example, to search items by an e-commerce system. In order to execute a search, there is a system for obtaining a search keyword and searching a target in some objects based on the keyword.
Non-patent Literature 1 discloses that, for example, a search system searches Web pages where cameras in the price range from $50 to $100 are posted using a search keyword “camera $50 . . . $100.”